Machine tools



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United States Patent 3,296,901 MACHINE TOOLS Kiyoshi Sawada, Numazu-shi,Japan, assignor to Toshiba Machine Co., Ltd., Tokyo, Japan Filed May 13,1964, Ser. No. 367,164 Claims priority, application Japan, May 14 ,1963,38/ 24,042 Claims. (Cl. 82--2) This invention relates to machine toolssuch as a vertical lathe and the like including a transversal girderadapted to support a movable tool and the like.

In a conventional vertical lathe, where a work mounted on a turn tableis cut the flatness of the upper surface of the work is mainlydetermined by the degree of horizontality of a line along which a toolpost travels on the transversal girder. In a vertical lathe of largesize, as the length of the transversal girder carrying the tool postincreases the amount of bending of the girder as the tool post travelsalong it will be increased owing to the weight of the transversal girderitself as well as the weight of the tool post. As a result it willbecome difficult to accurately cut the work having a horizontal plane.In order to obviate this difficulty the opposite supporting ends of thetransversal girder have been cut off so as to increase the height of themiddle portion thereof whereby to decrease the amount of lowering due tobending. With this construction, however, it has been difficult not onlyto perfectly compensate for the effect of such bending but also toeasily vary the degree of compensation to bending, to fit the meantemperature of the place where the machine is operated, when the machineis put on the base, and also to vary repeatedly the degree ofcompensation to bending to be caused due to aging of the material.Especially, in vertical lathes as it is not permissive to make too highthe height of the middle portion there was a danger of overcompensation.

It is the object of this invention to obviate the difficulty mentionedabove.

Further object of this invention is to provide an improved machine toolsuch as a vertical lathe wherein bending of the transversal girderthereof can be compensated by simple means.

According to this invention, in a machine tool having a transversal orhorizontal girder, a beam is provided along the girder and one or moremeans are interposed between a beam and the transversal girder to varythe degree of compensation to bending, said transversal girder being inparallel with said beam.

The features of the invention which are believed to be novel aresetforth with particularity in the appended claims. The inventionitself, however, as to its organization together with further objectsand advantages thereof, may best be understood by reference to thefollowing description taken in connection with the accompanyingdrawings, in which:

FIG. 1 shows a front elevation of a vertical lathe embodying thisinvention;

FIG. 2 shows a side view of the lathe shown in FIG. 1;

FIG. 3 is a graph showing comparison between the amounts of bending oftransversal girder of the prior art and that of this invention;

FIG. 4 shows a front elevation of a modification of this invention;

FIG. 5 is a graph showing the comparison between the amount of bendingof the transversal girder of the modified lathe shown in FIG. 4 and thatof the prior art;

FIG. 6 shows a cross-sectional view of the transversal girder of anothermodification of this invention; and

FIGURE 7 shows a perspective view of the connecting means.

Patented Jan. 10, 1967 "ice Referring now to FIGS. 1 and 2 of theaccompanying drawings, there is shown a vertical lathe comprising a pairof spaced apart columns 2 and 3 secured on a base 1, a transversal orhorizontal girder 4 with its opposite ends supported by the columns andtool posts 7 which are guided to move along the transversal girder 4 andcarry holders 6 for cutting tools 5 at their lower ends. As in theconventional lathe the tool posts 7 are fed by a lead screw 8. In arecess of the base 1 between the columns 2 and 3 is mounted a turn table10 adapted to support a work 11 to be turned.

In accordance with this invention a beam 12 is provided above and alongthe transversal girder 4 which is in parallel thereto. The girder andthe beam are interconnected by suitable connecting means such aspedestals 17, 18 and 19 having the same heights and replacable spacersor shims 14, 15 and 16. At the central portion of the span lengthbetween said columns 2 and 3, the shim 16 is made thinner than theothers i.e., shims 14 and 15 at the opposite ends, said shim 16 beingremovably attached to the upper surface of the pedestal 19 by means ofsetting bolts (not shown), which respectively rigidly fix the beam 12through each of holes 36 and 37 of the pedestal 1-9 and the shim 16,-andthe other setting bolts rigidly fix the girder 4 through holes 35 of thepedestal 19.

According to this invention constructed as above described as thecentral portion of the transversal girder 4 is connected to the beam 12by a connecting means having shorter length than those located at theopposite ends the central portion of the girder will be pulled upwardly.As a result even when the central portion is bent downwardly due to theweight of the tool posts 7 and or the weight of the girder itself, it isable to maintain the path of the tool posts 7 and or the weight of thegirder itself, it is able to maintain the path of the tool postssubstantially horizontal.

The amount of bending of the transversal girder is shown in FIG. 3wherein the abscissa indicates the distance along the girder and theordinate indicates the amount of bending. In FIG. 3 curve A representsthe amount of bending of the prior girder which is merely mounted uponthe columns 2 and 3, curve B that of the prior girder which is securelysupported by columns 2 and 3, and curve C represents the amount ofbending of the girder embodying this invention. As can be clearlyunderstood from these curves the amount of bending of the girderembodying this invention is far smaller than those of the prior art.

FIG. 4 shows a modified embodiment of this invention wherein atransversal girder 4 carrying tool posts 7 is supported by a pair ofspaced columns 2 and 3 mounted upon a turn table 10' and a hollow orannular work 11 is supported outside of the turn table 10.

Again, a beam 12 is disposed above and along the transversal girder 4and these members are connected together by connecting means 23, 24 and25 including replaceable shims 20-, 21 and 22, assembled with thecorresponding pedestals, it being understood that the thickness of thecentral shim 22 is made smaller than that of the outer shims 20 and 21to provide a similar function as described above. Further a screw means26 is vertically arranged between the under surface of the beam and theupper surface of the girder. Said screw means 26 has a bolt rigidlymounted on the upper surface of the girder and a nut. When the nut isthreaded on the bolt to be pushed toward the under surface of the beam,compression stress occurs in the vertical direction between the beam andthe girder to vary the degree of compensation to bending.

FIG. 5 shows the amount of bending of the horizontal girder of the latheshown in FIG. 5 wherein the abscissa indicates the distance along thegirder and the ordinate the amount of bending. Curve C represents theamount of bending of the girder embodying this invention as compared tothat of the prior art indicated by the curve D which shows that theamount of bending is greatly reduced by the novel connecting means ofthis invention.

While in the embodiments illustrated in FIG. 1, 2 and 4 the beam 12 islocated above the horizontal girder 4, it will be understood that thisinvention is by no means limited to this particular arrangement.

For example as shown in FIGURE 6, the transverse girder 30 may be formedso as to have a rectangular hollow cross section to house a beam 31. Aconnecting means 32 such as a screw is provided at the center of thegirder span, said girder being supported at its opposite ends on columns(not shown). By the adjustment of the screw, the degree of compensationto vertical bending may be varied. Other setting screws 33 and 34 shownin FIG- URE 6 are provided at opposite sides of the girder at suitablepositions in its longitudinal direction.

The operation of this modification is similar to that of the otherembodiment.

As can be clearly noted from the foregoing description bending andlowering of the transversal girder can be effectively compensated orprevented by connecting a transversal girder to a horizontal beamthrough one or more adjustable connecting means whereby to move a tooland the like along a substantially horizontally plane. Moreover evenwhen the compensation is effected by mean temperature variation due toseasonal circumstances or aging of the material, it can be easily andaccurately corrected.

Although specific embodiments have been disclosed to illustrate theinvention; it will be evident that the teachings apply to other kinds ofmachine tools and that many modifications and variations fall within thescope of this invention. It therefore is to be intended that within thescope of the appended'claims, the invention may be practiced otherwisethan as specifically described.

What is claimed is:

1. A machine tool comprising a horizontal girder supported at itsopposite ends, on columns spaced-apart, a beam extending along saidgirder and connecting means interconnecting said beam and said girder, aplurality of said connecting means being made thinner than the remainingconnecting means and made variable in height to vary the degree of thecompensation for the bending of said girder.

2. A machine tool according to claim 1 in which said horizontal girderincludes a part which extends with a part of said beam from one of itspositions supported by said columns.

3. A machine tool according to claim 1 in which each of said connectingmeans comprises a shim connected with a pedestal with setting bolts.

4. A machine tool according to claim 2 in which each of said connectingmeans comprises a shim connected with a pedestal with setting bolts.

5. A machine tool according to claim 2 in which said connecting meansconsists of a bolt and a nut.

References Cited by the Examiner UNITED STATES PATENTS 2,912,905 11/1959Berthiez 90-16 FOREIGN PATENTS 1,315,481 12/1962 France.

938,947 10/1963 Great Britain.

WILLIAM W. DYER, JR., Primary Examiner.

LEONIDAS VLACHOS, Examiner.

1. A MACHINE TOOL COMPRISING A HORIZONTAL GIRDER SUPPORTED AT ITSOPPOSITE ENDS, ON COLUMNS SPACED-APART, A BEAM EXTENDING ALONG SAIDGIRDER AND CONNECTING MEANS INTERCONNECTING SAID BEAM AND SAID GIRDER, APLURALITY OF SAID CONNECTING MEANS BEING MADE THINNER THAN THE REMAININGCONNECTING MEANS AND MADE VARIABLE IN HEIGHT TO VARY THE DEGREE OF THECOMPENSATION FOR THE BENDING OF SAID GIRDER.